GB2084257A - Transporting Coal Slurry by Ship - Google Patents

Abstract

A method of transporting coal in which coal sent forward in the form of a slurry is classified in accordance with the particle size of the coal, and the coal slurry other than a fraction thereof containing the fine particles not larger than a specified size is transported by ship. Arrangements for classifying the slurry and dewatering it are described, some of these being on board ship. <IMAGE>

Description

SPECIFICATION Method of Transporting Coal and Ships for Transporting Coal Slurries This invention relates to a method of transporting coal slurries and a ship and to coal slurry transport ships for use in the method.

Generally coal is transported on the land from coal mining areas to loading ports, where it is loaded into ships for transport on the sea. To reduce the cost of transport, it is common practice in recent years to pulverize coal to particle sizes of up to several millimeters and disperse the particles in water to obtain a coal slurry in the mining area, transport the coal slurry to a loading port through a pipeline and load the slurry into a ship for transport. With slurry transport ships, the coal slurry must be dewatered to the greatest possible extent during loading or navigation to achieve an improved transport efficiency and a reduced transport cost. However, when the coal slurry sent forward through a pipeline is loaded as it is into the ship, the slurry is extremely difficult to dewater as will be described below.When a slurry of large coal particles is conveyed through the pipeline, the slurry is easy to dewater after transport but causes marked wear on the pipe and requires a relatively high flow velocity, consequently necessitating increased power consumption and entailing a higher transport cost. Conversely a slurry of exceedingly small particles has a high viscosity and requires increased power consumption for transport. Thus the coal slurry to be transported has an optimum particle size distribution in view of the transport cost. For this reason, the slurry to be conveyed is adapted to contain large coal particles, for example, of about several millimeters in maximum size and also fine coal particles of up to several tens of microns in an amount not smaller than a specified proportion.

When loaded into a hold, such coal slurry initially contains the coal particles as substantially uniformly dispersed therein, but with the lapse of time, large particles settle to form a lower layer under an upper layer of floating small particles.

Slurries in holds are dewatered usually by drawing off water through a drain opening formed in the bottom of the hold and provided with a filter. If the above-mentioned coal slurry containing fine particles is drained by this method, the small coal particles floating in the upper layer will cover the lower layer of large coal particles with the progress of draining, consequently closing interstices, namely water channels, in the lower layer. This leads to a reduced draining efficiency, or in an extreme case, makes it impossible to drain the slurry.

Additionally small coal particles are likely to clog up the filter and result in a lower dewatering efficiency.

Summary of the Invention An object of the present invention is to provide a method of transporting coal in which the coal loaded into a ship in the form of a slurry can be dewatered with ease and can therefore be transported on the sea with an improved efficiency.

Another object of the invention is to provide a method of transporting coal by which coal can be transported from the mining area to a loading port on the land at a reduced cost.

These objects are fulfilled by a method of transporting coal comprising classifying coal supplied in the form of a slurry in accordance with the particle size of the coal and transporting by a ship the coal slurry other than a fraction thereof containing the fine particles not larger than a specified size.

Another object of the invention is to provide a coal slurry transport ship in which coal in the form of a slurry and loaded into its hold can be dewatered to the greatest possible extent to achieve an improved transport efficiency.

This object is fulfilled by a coal slurry transport ship having a hold for a coal slurry and means provided for the hold for dewatering the slurry.

Brief Description of the Drawings Figure 1 is a flow chart showing a method of this invention; Figure 2 is a view in vertical section showing a slurry separator; Figure 3 is a perspective view showing an apparatus for concentrating and solidifying a slurry of fine coal particles; Figure 4 is a perspective view showing a modified slurry separator; Figure 5 is a perspective view showing another modified slurry separator, Figure 6 is a view in longitudinal section showing a hold portion of a coal slurry transport ship embodying the invention; Figure 7 is a perspective view showing the hatch portion of the hold; Figure 8 is a view in vertical section partly broken away and showing a drain tube; Figure 9 is a side elevation partly broken away and showing means for raising and lowering the drain tube; Figure 10 is a plan view of Figure 9;; Figure 11 is a view in longitudinal section of a hold portion for showing a modified structure for supporting the drain tube; Figure 12 is a perspective view partly broken away and showing a hold portion of another coal slurry transport ship embodying the invention; Figure 13 is a view in longitudinal section showing the same; Figure 14 is a fragmentary view in longitudinal section showing a modified water guide; Figure 15 is a fragmentary view in longitudinal section showing another modified water guide; Figure 1 6 is a front view of Figure 1 5; Figure 17 is a view in section taken along the line S17-S17 in Figure 16; Figure 18 is a view in longitudinal section showing a hold portion of another coal slurry transport ship embodying the invention; Figure 19 is a view in section taken along the line S 1 9~S 19 in Figure 18;; Figure 20 is a view in longitudinal section showing a hold portion slightly different from the one shown in Figure 18; Figure 21 is a cross sectional view showing another coal slurry transport ship of the invention; Figure 22 is a plan view of Figure 21; Figure 23 is the combination of a perspective view showing a turning arm and a view in vertical section showing rotating means and vertically moving means therefor as arranged in corresponding relation; Figure 24 is a view in section taken along the line S24 S24 in Figure 23; Figure 25 is a front view for illustrating the operation of the turning arm; Figure 26 is a fragmentary bottom view showing a modified turning arm; Figure 27 is a front view showing another modified turning arm; Figure 28 is a fragmentary plan view showing another coal slurry transport ship embodying the invention;; Figure 29 is a view in section taken along the line 529-529 in Figure 28; Figure 30 is an enlarged view in section taken along the line S30 - S30 in Figure 28; Figure 31 is a fragmentary side elevation partly broken away and showing a screw conveyor on an enlarged scale; Figure 32 is a side elevation partly broken away and showing a modified screw conveyor; Figure 33 is a fragmentary enlarged view in section of Figure 32; Figure 34 is a flow chart showing another method embodying the invention; Figure 35 is a diagram showing a system including a granulating apparatus and adapted to practice the method of Figure 34; Figure 36 is a flow chart showing another method of the invention; Figure 37 is a flow chart showing another method of the invention;; Figure 38 is a fragmentary view in longitudinal section showing another coal slurry transport ship embodying the invention; Figures 39, 40 and 41 are cross sectional views showing a hold portion of Figure 38.

Figure 42 is a perspective view partly broken away and showing the hold portion; Figure 43 is a fragmentary view in longitudinal section showing another coal slurry transport ship embodying the invention; Figure 44 is a fragmentary perspective view partly broken away and showing another coal slurry transport ship embodying the invention; Figure 45 is a fragmentary perspective view showing a hold of Figure 44 on an enlarged scale; Figure 46 is a perspective view showing separators in Figure 44 on an enlarged scale; Figure 47 is a cross sectional view corresponding to Figure 46; Figure 48 is a fragmentary front view partly broken away and showing a slurry transfer duct in Figure 44 on an enlarged scale; Figure 49 is a view in section taken along the line S49-S49 in Figure 48;; Figure 50 is a front view partly broken away and showing a modified slurry transfer duct; Figure 51 is a bottom view corresponding to Figure 50; Figure 52 is a front view partly broken away and showing another modified slurry transfer duct; Figure 53 is a view in longitudinal section showing a hold portion of another coal slurry transport ship embodying the invention Figure 54 is a plan view showing the same; Figure 55 is a front view showing means for adjusting the angle of turn of a nozzle mounting pipe; Figure 56 is a view for illustrating the operation of injection nozzles; Figure 57 is a view in longitudinal section showing a hold portion of another coal slurry transport ship embodying the invention; Figure 58 is a plan view showing the hold portion of Figure 57; Figure 59 is a perspective view showing a flap and means for moving the flap;; Figure 60 is a fragmentary view in section showing the relation between the flap and a guide rail; Figure 61 is a side elevation of Figure 60; Figure 62 is a perspective view partly broken away and showing another coal slurry transport ship embodying the invention; Figure 63 is an enlarged view in vertical section showing a tray of Figure 62; Figure 64 is a view in vertical section showing a modified tray; Figure 65 is a plan view schematically showing a transport ship and system for practicing another method of the invention; and Figure 66 is a schematic diagram showing a granulating and classifying apparatus.

Description of the Preferred Embodiments Figure 1 is a flow chart showing a method of this invention.

With reference to Figure 1, coal is pulverized by a coal mill 2 installed at a coal mining area 1.

The coal is pulverized to particles up to about 3 mm if largest and about 0.1 to about 0.4 mm in average size. The pulverized coal is supplied to a slurry preparing apparatus 3 to obtain a slurry containing about 50% by weight of water. The particle size distribution of the pulverized coal and the concentration of the slurry are determined in view of the distance of transport of the slurry, the wear to be produced on the transport pipe, the possible clogging of the pipe, the quality of the coal, the characteristics of the coal mill 2 and the like. Thus the distribution and concentration are suitably variable in accordance with variations of these conditions.The coal slurry is transported through a pipeline to a loading port, where the slurry is separated by a slurry separator 4 into a fine particle coal slurry containing fine particles of 0 to 0.15 mm in size and a coarse particle slurry containing coarse particles of 0.15 to 3 mm in size. The particle size of 0.1 5 mm is thus set as the separation standard because it is difficult to dewater slurries containing fine particles of not larger than 0.15 mm in size. However, the separation standard is variable in accordance with the quality of the coal and other conditions. Figure 2 shows an example of useful slurry separators 4.

The illustrated separator 4 comprises an agitation tank 6 provided at its bottom portion with agitating blades 5 for directing the contents of the tank upward. An inlet duct 7 for a coal slurry feed and an outlet duct 8 for a coarse particle slurry are disposed on opposite sides of the tank 6 at its lower portion. At an upper portion of the tank 6. A fine particle slurry outlet duct 9 is provided at the same side as the slurry inlet duct 7. The fine particle fraction of the coal slurry introduced into the tank 6 through the inlet duct 7 moves upward in the tank 6 and flows out from the outlet duct 9, while the coarse particle fraction settles in the lower portion of the tank 6 and flows out from the outlet duct 8.

The coarse particle coal slurry thus separated is temporarily stored in a storage pond 10 and then loaded into the hold of a first transport ship 11.

The coal slurry is dewatered during navigation for a reduction of its weight to lessen the load, whereby the water content of the coal slurry to be discharged at a port of delivery is reduced to about 10% by weight. The coarse particle coal in the form of a solid mass is discharged onto the wharf of the port of delivery with a grab, or as converted to a slurry again. The coarse particles slurry thus loaded into the transport ship 11 and free from fine particles of up to 0.15 mm in size is easier to dewater and can be transported more efficiently and much less expensively than the unseparated coal slurry containing such fine particles.

On the other hand, the fine particle coal slurry separated is fed to an apparatus 12 for concentrating and solidifying the slurry. Figure 3 shows a useful example of such apparatus 12.

The illustrated apparatus 12 comprises a concentration tank 14 having a slanting bottom wall 13 and a header 15 at its upper end. The header 15 has a large number of slurry inlets 16 opened to the interior of the tank 14. A slurry collecting channel 17 extends widthwise of the tank 14 at its lower end. A slurry return duct 18 having a pump 19 thereon extends from one end of the channel 1 7 to the header 1 5. The tank 14 has at one side thereof a solid coal outlet 20 from which a slanting plate 22 for guiding solid coal extends to a solid coal depot 21 disposed obliquely below the tank 14 on the same side.

The fine particle slurry is introduced into the concentration tank 14, allowed to flow down the slanting bottom wall 13 and dried in the sun. The slurry portion flowing into and collected in the channel 17 is returned to the header 15 via the duct 18 and caused to flow down the slanting bottom wall 13 again. In this way the slurry is progressively concentrated by being circulated through the apparatus 12 without stagnation. The resulting solid mass of fine coal particles is forced out from the outlet 20 to a depot 21 by a bulldozer 23 at a specified time interval. The solid coal with a water content of 4 to 5% by weight is loaded into a second transport ship 24, carried to the port of delivery and discharged from the ship with a grab.The fine particulate coal remaining in the form of slurry in the apparatus 12 is stored in a storage pond 25, then loaded into a third transport ship 26, carried to the port of delivery and unloaded as a slurry.

Figure 4 shows another slurry separator 4 comprising aplurality of classifying basins 27 arranged side by side in a row. Openings 29 formed in the upper ends of the partitions 28 between the basins 27 are positioned in a staggered arrangement for overflowing the slurry.

The coal slurry fed to the most upstream classifying basin 27 (at the left end of Figure 4) through an inlet 30 flows downstream from basin to basin into the most downstream basin 27 (at the right end of Figure 4), overflowing the partitions 28 at the openings 29. In the meantime, coarser particles accumulate in upper basins 27, and finer particles in lower basins 27 with respectto the flow of the slurry.

Figure 5 shows another slurry separator 4 comprising a tray 31 for carrying and dewatering slurry provided at the terminal end of the slurry transporting pipeline at the loading port. The dewatering tray 31 comprises an upper tray member 32 and a lower tray member 33. The upper tray member 32 is connected to the pipeline and has a large number of drain apertures 34 in its bottom and a fiber filter 35 covering the upper surface of the bottom wall and the inner surface of its side walls. The upper tray member 32 is formed in a specified portion of its bottom with an opening 36 for discharging coarse particle coal slurry. The filter 35 is cut out at the portion corresponding to the opening 36.In communication with the discharge opening 36, a slurry supply duct 37 extends from the under side of the bottom wall to the bond 10 for the storage of coarse particle coal slurry. The lower tray member 33 coextensive with the upper tray member 32 is disposed below the tray member 32 as spaced therefrom by a specified distance for receiving the slurry flowing down from the upper tray member 32 and containing fine particles. The terminal end of the upper tray member 32 is connected to the coarse particle slurry storage pond 10, and the terminal end of the lower tray member 33 to the fine particle slurry storage pond 25. The lower tray member 33 is provided with a vibrator 38 for promoting separation and dewatering of the fed slurry. The fiber filter 35 is fastened to the upper tray member 32 by holders 39 arranged at specified spacing, such that the filter 35 is wholly replaceable when clogged up.

The coal slurry sent forward from the mining area 1 through the pipeline is fed to the upper member 32 of the dewatering tray 31. While the slurry flows through the upper tray member 32, a fraction of the slurry containing fine particles falls into the lower tray member 33 through the drain apertures 34, flows through the tray member 33 and is collected in the fine particle slurry storage pond. The coarse particle slurry separated from the fine particle fraction and dewatered to some extent flows into the supply duct 37 through the discharge opening 36 in the upper tray member 32 and is led into the coarse particle slurry storage pond 10.

Thus the dewatering tray 31 comprises an upper tray member 32 and a lower tray member 33 disposed below the member 32 and spaced apart therefrom by a specified distance, at least one of the bottom wall and side walls of the upper tray member 32 being provided with a filter 35 and a multiplicity of drain apertures 34 for discharging water containing fine particles.

Because of this construction, the tray 31 classifies the particles in the coal slurry flowing therethrough, affording a coarse particle slurry which has been dewatered to some extent.

Figures 6 to 11 show a ship embodying this invention for transporting a coal slurry while dewatering the slurry during navigation.

With reference to Figures 6 and 7, the transport ship has a slurry hold 40 provided with four guide tubes 43 arranged around a hatch 41 and extending through a deck 42. Drain tubes 44 extend downward into the hold 40 with their upper ends inserted in the guide tubes 43.

The main body 45 of the drain tube 44 comprises an upper portion serving as a casing portion 46, an intermediate portion as a filter portion 47 and a lower end portion 48. The filter portion 47 comprises an inner tube 49 and an outer tube 50. The inner tube 49 is formed with a large number of holes 51 which are out of alignment with like holes 52 formed in the outer tube 50. An inner filter 53 of metal netting and an outer filter 54 of nylon or like fiber over the filter 53 are fitted around the inner tube 49 in an annular space within the outer tube 50. These filters 53, 54 are tubular. The inner tube 49 has upper and lower threaded ends 49a and 49b which are screwed in the casing portion 46 and the lower end portion 48 respectively. The outer tube 50 has a threaded upper end 50a screwed on the inner tube 49. Indicated at 55 and 56 are rubber packings.The lower end portion 48 has a closed lower extremity, is tapered and has an interior space serving as a water accommodating space 57. An underwater pump 59 is retained in the lower end portion 48 by a rib 58. The underwater pump 59 has a downwardly opened inlet 59a and an outlet 59b connected to a drain pipe 60 in the form of a flexible hose. The drain pipe 60 extends outward from the drain tube main body 45 over a guide roller 61 at the upper end of the casing portion 46. A power supply cable for driving the pump 59 is incorporated into the drain pipe 60.

The guide tube 43 has a pair of rope guide tubes 62. Wire ropes 64 attached to connecting members 63 on the lower end of the drain tube 44 and extending through the rope guide tubes 62 support the drain tube 44 in suspension. Each of the ropes 64 is pad off from a winch 65 and passed over guide sheaves 66 and 67 on the upper and lower ends of the tube 62. The winches 65, ropes 64, rope guide tubes 62 and guide sheaves 66, 67 constitute means 68 for raising and lowering the drain tube.

The slurry will be drained by the following method. The ropes 64 are paid off from the winches 65 to lower the drain tube 44 along the guide tubes 43 in suspension (as shown on the right side of Figure 6) and place the drain tube 44 into the layer of slurry. The water in the slurry layer flows into the drain tube 44 through the holes 51, 52 in the inner and outer tubes 49, 50 and the inner and outer filters 53. 54 and is collected in the water accommodating space 57 in the lower end portion 48. The water is then discharged by the pump 59 through the drain pipe 60. The solid component of the slurry is prevented from flowing into the drain tube by the filters 53 and 54. Large solids are unable to pass through the holes 52 in the outer tube 50. The inner tube 49 supports the filters 53, 54 against the pressure of the slurry acting thereon.When the filters 53, 54 have sufficient strength, the inner tube 49 can be dispensed with.

After the slurry has been drained, the drain tube 44 is raised by the winches 65. The drain tube 44, when tapered in its entirety toward the lower end, can be withdrawn from the concentrated slurry layer easily. A vibrator, if mounted on the upper end of the drain tube 44, further facilitates the withdrawal of the tube.

Although the drain tube 44 projects high above the deck when raised, the tube 44 will not become an obstacle when the casing portion 46 is removed from the threaded end 49a, or if the upper portion of the tube 44 is made bendable.

As seen in Figure 11 the drain tube 44 may be turnably supported at its upper end by a pivot 70 on the under side of a hatch cover 69. In this case, a winch 72 is provided on the under side of the hatch cover 69 for taking up a wire rope 71 attached to the lower end of the drain tube 44.

With this arrangement, the drain tube 44 is used in its vertical suspended position for draining, while it is held along the under side of the hatch cover 69 when out of use as indicated in a broken line in Figure 11. The drain tube 44, when thus stored along the under side of the hatch cover 69, does not project above the deck and will cause no trouble.

With the transport ship shown in Figures 6 to 11, drain tubes having filters are placed into the hold for the removal of water from the coal slurry, so that the slurry can be dewatered smoothly through efficient preparatory and other work procedures.

When the drain tube is adapted to be brought into the hold along guide tubes, the drain tube is easily insertable into and withdrawable from the slurry layer. Especially it is easily withdrawable from the layer in a concentrated state.

The drain tube, when pivoted to the under side of the hatch cover, can be stored along the under side of the hatch cover. This assures effective use of the space available without permitting the drain tube to cause some trouble while it is out of use.

Figures 12 to 17 show another slurry transport ship of the dewatering type.

With reference to Figures 12 and 13, a lateral partition 74 within a hold 73 has at its lower portion a drain opening 76 provided with a filter 75. The water passing through the drain opening 76 is collected in a water receptacle 78 disposed under a bottom plate 77. The water receptacle 78 is connected to an inlet of a draining pump 79.

The bottom plate 77 is formed at suitable portions with a plurality of drain openings 80, under which there is provided a water receptacle 81 connected to the inlet of the draining pump 79. The drain opening 80 has a perforated plate 82. Fiber water guides 83 and 84 each in the form of an endless belt are disposed respectively on a central vertical portion 74a and a lower slanting portion 74b of the lateral partition 74.

The water guide is reeved around a pair of arms 85 fixed to each of the vertical and slanting portions 74a and 74b. The opposed upper and lower water guides 83 are in contact with or in proximity to each other. The upper water guides 83 are so positioned that their upper ends will be above the layer of coal particles, 86, placed into and settling in the hold 73. The water guides 83 and 84 are made endless so as to be turnable when subjected to the pressure of the particle layer 86 that would otherwise rupture the guide.

Water guides 87 of fiber extends on the bottom plate 77 longitudinally thereof. A lateral water guide 89 of fiber at right angles with the longitudinal water guides 87 extends on both the bottom plate 77 and longitudinal partitions 88.

The drain openings 80 are positioned under the intersections of the longitudinal and lateral water guides 87 and 89. Both ends of the lateral water guide 89 are substantially at the same level as the upper ends of the upper water guides 83. The water guides 83, 84, 87 and 89 may be made of the same material as the fiber filter, or sponge or the like, such that the guide will not be clogged up with particles and is permeable to a liquid only.

Even when a coarse particle coal slurry separated from fine coal particles is placed in the hold, large particles in the slurry will settle as a lower layer with the lapse of time under an upper layer of small particles. Thus the small coal particles floating to form the upper layer cover the underlying layer of large coal particles, with the resulting likelihood of closing the interstices (water channels) in the mass of slurry and presenting difficulty in dewatering the slurry.

It is now assumed that when a coal slurry is loaded into the hold 73 provided with the above means and the pump 79 is operated to dewater the slurry, the water channels through the layer 86 of particles are clogged up. Even in this case, the upper ends of the upper water guides 83 and of the lateral water guide 89 are positioned above the particle layer 86, so that the water over the layer 86 is partly led from the upper ends of the upper guides 83 through the guides 83, then through the lower guides 84 to the drain opening 76, while the water is also partly led from the upper ends of the lateral guide 89 through the guide 89 to the drain openings 80. Consequently the water is discharged by the pump 79.Further the water passing through the particle layer 86 and along the outer periphery thereof and reaching the longitudinal and lateral partitions 88, 74 and the bottom plate 77 is led through the water guides 83, 84, 87 and 89 to the drain openings 76, 80 for discharge.

Although two kinds of water guides 83, 84 and 87, 89 are used in the above embodiment, the lateral water guide 89 on the longitudinal partition 88 is replaceable by endless water guides 83, 84, or conversely, water guides similar to the lateral guide 89 are usable in place of the endless guides 83, 84 on the lateral partition 74.

The two water guides 83, 84 are further replaceable by a single water guide 90 in the form of an endless belt as seen in Figure 14. The guide 90 is held by an arm 91 extending along the junction between the vertical portion 74a and the slanting portion 74b of the lateral partition 74.

The endless water guides 83, 84 are further replaceable by a single stationary water guide 92 as shown in Figures 15 to 17. Indicated at 93 is an inverted U-shaped frame secured to the lateral partition 74 for holding the guide 92, and at 94 a holding plate disposed over the outer periphery of the guide 92 within the frame 93. The holding plate 94 is pressed against the guide 92 by a multiplicity of bolts 95 screwed into the holding frame 93.

With the transport ship shown in Figures 12 to 1 7 and having water guides provided on suitable portions of the inner surfaces of the hold and extending to drain openings, water is led through the guides to the drain openings to dewater the coal slurry placed in the hold even when the interstices, namely water channels, in the layer of deposited coal particles are clogged up.

Accordingly the slurry can be drained within a much shorter period of time than is conventionally possible.

Figures 18 to 20 show another slurry transport ship of the dewatering type.

The ship has a hold 100 shown in Figure 18. At the four corners of a hatch cover 101 inside thereof, there are take-up rollers 103 for paying off cables 102. These rollers 103 are covered with covers 104 and are rotatable at the same time by unillustrated drive means. The cables 102 extending downward from the rollers 103 are attached at their lower ends to the four corners of a dish-shaped dewatering frame 105 including a frame member 106 in the form of a rectangular ring. A filter 107 extending over the frame member 106 and attached to the under side thereof is reinforced by a lattice-like framework 108. Metal netting, fibrous or various other materials are useful for the filter 107. The filter 107 is bulged downward in its center.The frame member 106 forming the side walls of the dewatering frame 105 is provided therearound with a pneumatically inflatable annular buoy 109 serving as a float and communicating with air supply-discharge means (not shown). A draining pump 110 is disposed in the center of the dewatering frame 105. The pump 110 has an outlet pipe 111 connected by a drain pipe 112 to a discharge hose 113 on an upper portion of a side wall of the hold 100.

At the loading port, the cables 102 are wound on the rollers 103 to store the dewatering frame 105 inside the hatch cover 101 as indicated in a two-dot-and-dash line in Figure 18, and the hatch cover 101 is then removed to open the hatch 114. A coal slurry is loaded into the hold 100 through the hatch 114. With the lapse of time, large coal particles of great specific gravity settle to form a lower layer S1, while small coal particles of reduced specific gravity float to form an upper layer S2. Thus the upper layer S2 contains fine coal particles suspended in water.

The cables 102 are then paid off from the rollers 103 to lower the dewatering frame 105. At the same time, the buoy 109 is inflated with air, and the frame 105 is thereafter floated on the surface L1 of the slurry water. With the dewatering frame 105 floating on the water surface L1, the rollers 103 are made free to pay off the cables 102. In this state, the buoy 109 prevents the slurry water from flowing into the dewatering frame 105 over the frame member 106. Since the dewatering frame 105 floating on the surface L1 is dishshaped, the filter 107 is held immersed in the slurry water, permitting water W alone to penetrate the filter 107 and flow into the frame 105 to separate the water from coal particles.

When the draining pump 110 is subsequently operated, the water W is discharged by the pump 110 through the outlet pipe 112 and hose 113.

This lowers the level of the slurry water, allowing the frame 105 to follow the water level under gravity. When the draining operation is continued, the upper layer S2 is almost completely dewatered as indicated in a dot-and-dash line in Figure 18, whereby the frame 105 is placed on the lower layer S1. When the pump 110 becomes unable to draw off any water, the cables are taken up on the rollers 103 to raise the frame 105 and store the frame inside the hatch cover 101. At the same time, air is released from the buoy 109 to contract the buoy.

Although the single dewatering frame 105 is used for the hold 100 as described above, the slurry in a single hold 11 5 can be dewatered with use of a plurality of dewatering frames 11 6 as shown in Figure 20, which shows frame members 118, buoys 119, draining pumps 120, cables 121, rollers 122, a hatch cover 123 and an upper deck 124.

While the dewatering frame in the foregoing embodiment is suspended from the hatch cover or upper deck, a separate support is alternatively usable for suspending the dewatering frame. The term "dish-shaped" used for describing the dewatering frame refers generally to those in which the peripheral portion is higher than the center portion. Thus the dewatering frame, for example, may have a recessed center portion.

With the transport ship shown in Figures 18 to 20 in which the slurry is dewatered always in the vicinity of the surface of the slurry water, the reduction in draining efficiency due to the clogging of the filter can be minimized. Further the dewatering frame, which is kept floating on the surface of the slurry water at all times by a float, is caused by gravity to follow the descent of water level due to draining, so that the apparatus is operable without necessitating additional equipment and is also easy to handle.

Figures 21 to 27 show another slurry transport ship of the dewatering type.

The ship has a hold 234 provided in its bottom with drain openings having a filter (not shown).

Rotary shafts 237 each carrying a turning arm 236 at its lower end extend from the top wall 235 of the hold 234. The rotary shafts 237 are disposed, for example, at the four corner portions of a hatch 238, such that the entire area of the hold 234 can be covered with the paths of rotation of the turning arms 236 to the greatest possible extent as seen in a plan view (Figure 22).

The turning arm 236 comprises a plurality of segments 236a of box-shaped cross section which are joined together with one fitted in another. The segments 236a are connected to one another by pins 239 and are slightly pivotally movable upward and downward relative to one another but are not movable laterally thereof at the connected portions. The turning arms 236 is provided on its under side with a large number of stirring blades 240 which are arranged at suitable spacing longitudinally thereof. The stirring blades 240 may be inclined with respect to the lengthwise direction of the arm 236 as seen in Figure 26, or may be perpendicular to the lengthwise direction. A conical projection 241 extends from the lower end of the rotary shaft 237.

The rotary shaft 237 has a hollow upper portion which is inserted in a rotation trnnsmittiflg tube 242 rotatably supported on the top wall 235 of the hold 234 and which has a screw rod 243 extending thereinto. The screw rod 243 is rotatably supported by a support member 244 on the top wall of the tube 242 and is screwed into a threaded member 245 within the rotary shaft 237. Thus the shaft 237 is suspended from the screw rod 243. The screw rod 243 is coupled to a portable air motor or like drive means. The drive means, screw rod 243, support member 244 and threaded member 245 constitute means 246 for vertically moving the rotary shaft 237.

Projections 247 and 248 meshing with each other are provided respectively on the inner surface of the rotation transmitting tube 242 and on the outer surface of the rotary shaft 237. A gear 249 is externally formed on the lower end of the tube 242 and is in mesh with a drive pinion 250 coupled to an air motor or drive means. The drive means, drive pinion 250, gear 249, tube 242 and projections 247, 248 provide means 251 for rotating the shaft 237. Indicated at 252 is a member for supporting the drive pinion 250.

The above arrangement operates in the following manner. While not in use, the turning arm 236 is pulled up to and stored inside of the top wall of the hold, i.e., on the rear side of the upper deck inside the hatch coaming, with the shaft 237 retracted in the tube 242 as seen in Figure 23. When the turning arm is to be used, the screw rod 243 is rotated to lower the rotary shaft 237, causing the lower end projection 241 of the shaft 237 to penetrate a shell-like layer formed in the top portion of the slurry within the hold 234. The arm 236 is turned by the shaft 237 through the tube 242 to break down the shell-like top layer of the slurry with the stirring blades 240.

At this time, the rotary shaft 237 is held stably to smoothly turn the arm 236, by being supported at its upper end and also by the shell-like layer pierced with its lower end projection 241. Since the arm 236 comprises the segments 236a which are connected to one another upwardly and downwardly movably as described above, the arm 236 is flexible in conformity with the configuration of the upper surface of the shell-like layer, with the result that the arm is turnable smoothly without any trouble. Torque can be transmitted from the tube 242 to the shaft 237 irrespective of the level of the shaft 237 because the projections 247 and 248 are used for transmission. When the shell-like layer is broken at the top portion of the slurry, air flows into the slurry smoothly, whereby the water component of the slurry is smoothly removable from the bottom of the hold 234.

The turning arm 236 may be provided at a corner of the hold 234 as indicated at 236' in Figure 22 so as to turn reciprocatingly over an angle of 90 degrees, or may be provided close to a side wall of the hold 234 as indicated at 236" in Figure 22 so as to turn reciprocatingly over an angle of 180 degrees.

Further as shown in Figure 27, the turning arm 236 may be in the form of an integral member attached to the lower end of the rotary shaft 237 slightly turnably upward and downward. A large number of turning arms 236 may be attached to the rotary shaft 237 as arranged radially.

With the transport ship shown in Figures 21 to 27, the turning arm having stirring blades and attached to a vertically movable rotary shaft, when turned, easily breaks up the shell-like layer of fine particles in the top portion of slurry, permitting unimpeded flow of air into the slurry to assure smooth removal of water from the slurry via the bottom of the hold. The arm is smoothly turnable with stability since the lower end conical projection piercing the shell-like layer serves as a support for the arm.

Figures 28 to 33 show another coal slurry transport ship having an agitator by which the coarse particle coal held in its hold and dewatered during navigation is made into a slurry again at a port of delivery.

The ship has a hold 125 of double bottom construction 126. A slurry outlet 127 formed in the center of the inner bottom plate 132 is in communication with a discharge pump 129 via a valve 128. A slurry outlet duct 130 is connected to the pump 129. A screw conveyor 131 extends from each of the four bottom corners of the hold 125 to the slurry outlet 127. The screw conveyor 131 can be mounted on the inner bottom plate 132 with bearings, but in the present embodiment, the lower half of the conveyor 131 is accommodated in a channel of semicircular cross section formed in the bottom plate 132. The screw conveyor 131 is coupled at its base end to drive means 135 by way of transmitting means 134. The conveyor has a blade 131 a and a water pipe 136 extending along the helical outer periphery of the blade.The base portion of the water pipe 136 is fitted in the base end (see Figure 31) or the forward end (see Figure 29) of the conveyor 131 and connected to a conduit 138 by a rotary joint 137. The helical portion of the water pipe 136 is provided with jet nozzles 141 at specified spacing.

When a mass of coal particles dewatered to some extent during navigation is to be made into a slurry again at the port of delivery, the screw conveyors 131 are driven, with water forced into the water pipes 136 to inject the water into the mass through the jet nozzles 141. The water may be supplied from a suitable location on the land or the like. While thus being agitated effectively, the coal particles are made into a slurry again and led into the slurry outlet 127.

In place of the water pipe 136 and jet nozzles 141, a multiplicity of jet nozzles 144 may be provided on the rotary shaft portion 143 of a screw conveyor 142 to force out water from between the adjacent portions of a blade 142a as seen in Figures 32 and 33. Alternatively the nozzles 144 may be used in combination with the nozzles 141. With reference to Figure 33, the jet nozzles 144 are implanted in the shaft portion 143 between the adjacent portions of the blade 142a. The forward end face 144a of the jet nozzle 144 is flush with the outer periphery 143a of the shaft portion 143. The orifice 145 of the nozzle communicates through a passage 147 with a fluid supply channel 146 formed in the shaft portion 143 along its axis. The jet nozzles 144 are arranged on a helical phantom line on the outer periphery of the shaft portion 143. Indicated at 148 is means for driving the screw conveyor, at 149 a bearing, and at 1 50 a rotary joint having an internal passage 151 for holding unillustrated liquid supply means in communication with the fluid supply channel 146.

With the transport ship shown in Figures 28 to 33, the coal slurry can be discharged from its hold rapidly for unloading. Especially when the jet nozzles are adapted to discharge water in a suitable direction, the reaction of the discharge can be utilized for supplementing the power needed for the rotation of the screw conveyor.

Figure 34 is a flow chart showing another method of the invention.

Figure 34 is similar to Figure 1 in that the coal pulverized by a coal mill 153 at a coal mining area 152 is fed to an apparatus 154 for preparing a slurry, which is transported to a loading port through a pipeline. At the loading port, the coal slurry is temporarily stored in a slurry pond 155 (see Figure 35). The slurry is then led through a supply duct 156 into the upper end of a first liquid cyclone 157, in which the slurry is wet classified into a fraction of coarse particles, for example, larger than 0.15 mm in size and a fraction of fine particles. To assure wet classification effectively, the latter fraction from the first liquid cyclone 157 is fed to a second liquid cyclone 1 58 disposed alongside the cyclone 157, whereby the fraction is further subjected to wet classification. Thus the first and second liquid cyclones 157 and 158 constitute a slurry separator 159.The coal slurry thus obtained and containing coarse particles of larger than 0.15 mm is led through ducts 160 and 161 into a pond 162 for storage. As is the case with Figure 1, the coarse particle slurry is loaded into a transport ship 1 63.

On the other hand, the fine particle coal slurry containing particles of up to 0.15 mm and separated from the coarse particle slurry is sent through a duct 164 to a thickener 165, in which the slurry is thickened by settling. The thickened fine particle slurry is run off from the bottom of the thickener 165 and fed to a primary granulating tank 168 of a two-stage granulating apparatus 167 via a duct 166. The supernatant in the thickener 165 is discharged via an overflow trough 169. Fuel oil or like binder is then introduced into the primary granulating tank 168 through a duct 170. The fine particle slurry and the binder are mixed together by being vigorously agitated by a homogenizer or like agitator.The mixture is introduced into a secondary granulating tank 1 71, in which it is gently agitated, for example, by a device (not shown) having agitating blades of metal net to form the fine particles into granules. Since coal and oil generally have affinity for each other, fine coal particles are joined together with fuel oil or like binder adhering to the surfaces of the particles for granulation. Examples of useful binders are fuel oil, kerosene, gas oil, residiuum oil and vegetable oils. The slurry containing the granules is introduced into the upper end of a third liquid cyclone 1 73 through a duct 1 72, whereby the granules are separated from the liquid by wet classification. The granules are sent to a storage pond 175 through a duct 174 and loaded into a transport ship 176.The granules may be sent to the storage pond 162 and loaded into the ship for transporting the coarse particle slurry. The coarse particle slurry and granules may be dewatered after loading. The liquid drawn off from the top.of the cyclone 173 is predominantly water, but if the liquid contains a small amount of ungranulated fine coal particles, the liquid is returned to the granulating apparatus 167 via a duct 177 to completely recover the fine particles in the form of granules.

With the method shown in Figures 34 and 35, a coarse particle fraction is separated from a slurry of particulate coal by wet classification, a binder is then added to the remaining portion of the slurry containing fine particles to granulate the fine particles, and the grains or granules are then separated from the liquid for the recovery of coal from the slurry, so that only the fine particles in the slurry need to be granulated. Consequently' coal can be recovered from the slurry very efficiently by treating a smaller amount of particles with a smaller amount of binder for a shorter period of time than when the particles in the slurry are all granulated. Moreover, the coal recovered, which comprises granules and coarse particles having large sizes, is highly permeable to water and easy to drain.This greatly facilitates the dewatering, drying and other procedures to be followed for the coal recovered, consequently assuring efficient recovery of particulate coal from the slurry. Granulation of fine coal particles further serves to remove ash from the coal. More specifically stated, the coal slurry contains fine particles of ash (inorganic substances) produced by the pulverization of coal and having no affinity for fuel oil or like binder. Accordingly during the granulation of fine coal particles, the ash does not adhere to the binder but is separated from the granules of fine coal particles, whereby the ash can be removed from the coal recovered.

Figure 36 is a flow chart showing another method of the invention.

With reference to Figure 36, coal is pulverized by a coal mill 181 at a coal mining area 180. The coal is pulverized to a maximum size, for example, of about 3 mm. Until a slurry of fine coal particles is returned from the unloading port as will be described later, the coal is finely divided to obtain fine coal particles of up to 0.075 mm in size. The pulverized coal is fed to a slurry preparing apparatus 182 along with water to obtain a slurry.

The particle size distribution of the slurry is so adjusted that about 20% by weight of all the coal particles are fine particles of the above-mentioned size. The coal slurry is conveyed through a pipeline to a loading port, where the slurry is fed to a slurry separator 183 and thereby separated into a slurry of fine coal particles up to 0.075 man in size and a slurry of coarse coal particles 0.075 to 3 mm in size.

The coarse particle coal slurry is stored in a storage pond 184 and then loaded into a transport ship 185 as is the case with Figure 1.

On the other hand, the fine particle coal slurry is returned as it is to the coal mining area through a pipeline. This slurry and coarsely divided coal 0.075 to 3 mm in particle size are fed to the slurry preparing apparatus 182 to prepare a slurry in which about 20% by weight of the coal particles are fine particles, like the one already produced.

The slurry is conveyed to the loading port through the pipeline. After the fine particle coal slurry has been returned to the coal mining area, there is no need to finely divide the coal to particle sizes of up to 0.075 mm, but the coal mill 181 needs to give only coarsely divided coal of 0.075 to 3 mm in particle size. Thus with use of the coarsely divided coal and the returned fine particle coal slurry, a slurry is prepared which has the desired particle size distribution and which can be continuously transported by the pipeline with a relatively small power.

The particle size of 0.075 mm is adopted as the separation standard for the following reasons.

For the reduction of the transport cost, the coal slurry must have incorporated therein finely divided coal, up to 0.075 mm in size, which, however, is costly to prepare at the coal mining area. Moreover, slurries containing such fine coal particles are very difficult to dewater. When a slurry of large coal particles is conveyed through a pipeline, the slurry is easy to dewater after transport but causes marked wear on the pipe and requires a relatively high flow velocity, consequently necessitating increased power consumption and entailing a higher transport cost. For this reason, it is practice to convey a slurry which contains both large coal particles and fine coal particles, such that the coal particles are about 2 to about 3 mm in maximum size and about 0.1 to about 0.4 mm in average size and includes fine particles of up to 0.075 mm in an amount of about 20% by weight.Such slurry is less likely to wear the pipe and can be transported at a reduced velocity and therefore at a lower cost but is difficult to dewater after transport since it contains fine coal particles. Additionally coal must be finely divided to obtain fine particles for the preparation of the slurry at the coal mining area.

With the method illustrated in Figure 36, however the fine particle coal slurry separated at the loading port is returned as such to the coal mining area through a pipeline, so that the remaining coarse particle coal slurry is easy to dewater. Moreover, since the fine particle slurry returned to the mining area is reused for the preparation of a coal slurry at the mining area, the slurry can be conveyed less expensively due to the presence of the fine particles. Additionally there is substantially no necessity for fine pulverization to obtain fine particles needed for reducing the transport cost. Accordingly the slurry can be prepared, conveyed through the pipeline and dewatered at reduced costs.

Figure 37 is a flow chart showing another method of this invention.

Figure 37 is similar to Figure 1 in that the coal pulverized by a coal mill 187 at a coal mining area 186 is fed to a slurry preparing apparatus 188 to obtain a coal slurry, which is conveyed to a loading port through a pipeline. At the loading port, the coal slurry is temporarily stored in a storage pond 189 and then loaded into a transport ship 190 as such.

As seen in Figures 38 and 42, the ship 190 has a number of holds 193 arranged longitudinally thereof and defined by lateral partitions 191 and opposed side walls 192. A large number of slurry outlets (openings) 194, which are closable, are formed in an upper portion of the lateral partition 191 of each hold 193. A slurry withdrawing opening 197 communicating with a slurry discharge duct 196 is disposed outside a lower slanting portion 195 of the partition 1 91. The discharge duct 196 extends through the interior of a bottom wall 198 of double construction to a slurry storage pond 199 on the shore and has a pump 200. A large number of dewatering filters 201 is provided at the lower end of the lateral partition 191. A water collecting bilge well 202 is disposed inside the bottom wall 198 at its one end.A water withdrawing opening 203 inside the bilge well 202 communicates with a drain pipe 204 extending outward from the ship.

The slurry S sent forward from the storage pond 189 is charged into the hold 193 as shown in Figure 39 and is allowed to stand for a specified period of time. Consequently the slurry S separates into two layers, namely a coarse particle lower layer S1 and a fine particle upper layer S2, as seen in Figure 40. When the slurry outlets 194 are then opened, the upper layer S2, namely the fine particle coal slurry, flows out from the hold 193 through the outlets 194, descends the outer side of the lateral partition 191 and is collected under the lower slanting portion 195 of the partition outside thereof. The fine particle slurry is then returned to the storage pond 199 on the shore via the discharge duct 196. As a result, the lower layer S1 only remains within the hold 193 as seen in Figure 41.During navigation, the lower layer S1, namely the coarse particle coal slurry, is drained by the dewatering filters 201.

The water is collected in the bilge well 202 and run off from the ship via the drain pipe 204.

The fine particle coal slurry returned to the pond 199 may be concentrated for solidification as seen in Figure 1, or granulated as shown in Figure 34, or returned to the coal mining area in the form of a slurry as seen in Figure 36.

Figure 43 shows a transport ship slightly different from the one described above.

With reference to Figure 43, a hold 205 for fine particle slurry is positioned in the center of a longitudinal arrangement of many holds 193. A slurry discharge duct 196 is connected via a pump 200 to a slurry duct 206 extending over the upper deck into the fine particle coal slurry hold 205. With the exception of the above feature, the ship is similar to the one shown in Figures 38 to 42.

With the present embodiment the coal slurry conveyed through a pipeline is placed into the holds 193. As is the case with the preceding embodiment, fine particle coal slurry is collected under the lower slanting portion 195 of each hold 193 outside thereof, with coarse particle coal slurry remaining in the hold 193. The fine particle slurry is sent into the hold 205 via the duct 206 by the pump 200. The fine particle slurry is discharged as such at the port of delivery by a pump.

Figures 44 to 52 show another modified transport ship.

With reference to Figure 44, the ship has a number of holds 208 divided by lateral partitions 207. As seen in Figure 45, a large number of overflow openings 209 are formed in an upper portion of the lateral partition 207 of the hold 208. The openings 209 are provided with an unillustrated movable door for vertically adjusting the position of the lower edges defining the openings 209. A slurry withdrawing opening 212 communicating with a slurry transfer duct 211 is disposed outside a slanting lower portion 210 of the partition 207. The transfer duct 211 thus communicating with all the withdrawing openings 212 extends through the interior of a bottom wall of double construction to a pump 214, from which the duct 211 further extends to separators 213 above the holds 208.The portion of the duct 211 extending from the pump 214 to the separators partly serves as a granulating tube for mixing a fine particle coal slurry and a binder together by stirring and forwarding the mixture as shown in Figures 48 and 49. More specifically, a rod 215 in alignment with the axis of the transfer duct 211 is provided in a short straight portion 21 la of the duct 21 1. One end of the rod 21 5 is rotatably and liquid-tightly supported by an outer corner portion 211 b of the straight portion 211 a at its one end. The other end of the rod 215 rotatably and liquid-tightly extends through an outer corner portion 211 c of the straight portion 21 1a at the other end thereof and is connected to unillustrated drive means.The rod 215 is provided at some locations with stirring blades 216 of metal netting, with a clearance a formed between the outer periphery of the blade 21 6 and the inner surface of the duct 211. The transfer duct 211 has a binder inlet (not shown) at a suitable portion.

As shown in Figures 46 and 47, each of the separators 213 comprises a main body 218 in the form of an elongated box and movably extending across a hatch coaming 217, and a filter 219 extending over the entire inner area of the main body 218 and positioned at an intermediate portion of its height. The main body 218 has a slurry inlet 220 at its one end on the upper side of the filter 219 and a water outlet 221 at the other end thereof on the under side of the filter 219.

The filter 219 is so inclined that it is at a higher level toward the slurry inlet 220. The filter 219 has in its center a coal inlet tube extending through the bottom wall of the main body 218 and opened to the hold 208. The slurry inlet 220 of the separator 21 3 is connected to the slurry transfer duct 211 by a flexible tube 223. The water outlet 221 of the separator 21 3 is connected by a flexible tube 224 to a drain pipe 225 one end of which extends to the land. The transport ship further has a slurry loading duct 226 extending from a slurry storage pond on the shore to upper portions of the holds 208.

A slurry of particulate coal is supplied from the storage pond on the shore to the holds 208 through the loading duct 226. While thus loading the slurry, the overflow openings 209 are opened to a suitable degree to cause supernatant water containing fine coal particles to overflow the lateral partitions 207 through the openings 209.

The water outside the partitions is led into the withdrawing openings 212 into the transfer duct 211 by the pump 214. While the fine particle coal slurry is being passed through the duct 211 to the separators 213, a binder comprising fuel oil or the like is admixed with the slurry by stirring in the granulating tube to granulate the fine particles in the slurry. More specifically fine coal particles in the slurry flowing through the duct 211 and the binder are mixed together by being stirred with the blades 21 6, whereby fine coal particles are adhered to relatively large coal particles to form agglomerates, namely grains or granules. The movement of fine coal particles at this time is indicated by an arrow in Figure 49.This movement is different from that heretofore observed in a static mixer in which the duct is provided with only bladelike blocking plates or in a line mixer comprising an agitator having usual blades. Thus the movement of coal granules and fine coal particles within the duct 211 or the rolling motion thereof on the duct wall serves effectively for the progress of granulation. The coal granules formed in the straight portion 211 a of the duct 211 flow downstream through the clearance a. Further coal granules formed earlier rapidly fall between the stirring blades 216, permitting other fine coal particles to form granules smoothly. With fine coal particles thus granulated, the slurry is placed onto the filter 219 of the separator 21 3 through the inlet 220.The slurry containing the granules flows down the filter 219, while permitting ash-containing water to pass through the filter 219 to the lower portion of the main body 218 and flow out through the water outlet 221. On the other hand, the granules of large size remain on the filter 219 and pass through the inlet tube 222 into the hold 208. The separator 213 is reciprocated on the hatchcoaming 217 at a relatively low speed longitudinally of the ship. The slurry fed to the separator 213 contains granules of large size only and is therefore easy to dewater and separate.

The water run off from the water outlet 221 is sent through the drain pipe 225 to suitable means on the shore, whereby the ash is removed from the water. The water is then led to a pond on the shore and reused as slurry water.

Although the granules of fine coal particles are added to the coal slurry separated from fine coal particles in the above embodiment, the granules can be placed into a separate hold.

As seen in Figures 50 and 51, the granulating tube included in the slurry transfer duct may comprise bent duct portions 227 provided in an intermediate part of the transfer duct 211 and each including stirring blades 228, the bent duct portions being provided in a plurality of stages.

Each of the bent duct portions 227 comprises a horizontal tube 227a and a bent tube 227b extending obliquely upward from the horizontal tube 227a and having a closed end 227c. A rod 229 disposed in the bent tube 227b and having stirring blades 228 rotatably extends through the closed end 227c and is connected to an unillustrated drive means. The junction 230 between the horizontal tube 227a and the bent tube 227b is connected to one end of the horizontal tube 227a of another bent duct portion 227. Thus the bent duct portions 227 are joined to one another in stages.

The coal slurry in the bent duct portions 227 moves as indicated by arrows and is effectively mixed with the binder, whereby the coal can be granulated efficiently.

Alternatively the stirring means may comprise a rod 232, stirring blades 231 mounted on the rod, and radial blades 233 attached to each side of the blade 231 as seen in Figure 52.

Figures 53 to 56 show another slurry transport ship having coal slurry separating means.

The ship has holds 253 arranged longitudinally thereof for containing a coal slurry and empty chambers 254 between the holds 253. Drain openings 256 formed in an upper portion of the rear wall 255 of the hold 253 are in communication with the empty chamber 254.

The drain opening 256 may be in the form of a cutout or an aperture. A drain channel 257 is provided at the bottom of the empty chamber 254. The hold 253 is provided at its bottom with bottom drain openings 258 communicating with the empty chamber 254. A fine particle coal slurry withdrawing duct 259 is disposed at the bottom of the empty chamber 254.

Two nozzle mounting pipes 261 are positioned some distance below the top wall of the hold 253 and extend along opposite side edges of a hatch 260. Each of the mounting pipes 261 has a multiplicity of injection nozzles 262 arranged longitudinally thereof at suitable spacing. One end of the pipe 261 is connected by a water supply conduit 264 to a pump 263 for supplying highpressure jet water. Pressurized air or like highpressure fluid is usable in place of water. The nozzle mounting pipe 261 is rotatably supported at its opposite ends by support members 266 attached to the top wall 265 of the hold 253 and is provided with means 267 for adjusting the angle of turn thereof.The angle adjusting means 267 comprises a lever 268 fixed to the pipe 261 and a screw rod 269 rotatably connected at its one end to the lever and in screw-thread engagement with a threaded member 270 on the top wall 265 of the hold 253. The screw rod 269, when turned by a handle 298, turns the injection nozzles 262 to a substantially horizontal position or to an obliquely upward position as seen in Figure 56. Preferably the nozzles 262 on the pipe 261 are made turnable toward the front or rear by some means. However, the injection nozzles 262 may be fixed as inclined toward the drain openings 256.

With the arrangement described above, the supernatant water of the coal slurry in the hold is discharged from the drain openings 256 into the empty chamber 254. The fine particles floating in the upper layer of the slurry can also be discharged in the following manner. Water is injected into the upper layer of the coal slurry (i.e.

about 1/5 portion of the height of the load) from the nozzles 262 in horizontal position to agitate the layer. The injection nozzles 262 are then turned obliquely upward toward the drain openings 256 to force the floating fine particles toward the openings 256 with the injected water and discharge them into the empty chamber 254.

The fine particulate coal can be discharged even when the injection nozzles 262 are fixedly directed toward the drain openings 256. Since the fine coal particles are thus removed from the upper layer of the slurry, no covering will be formed with fine particles, permitting air to pass through the slurry effectively and enabling water to flow out smoothly from the bottom drain openings 258 of the hold 253.

With the transport ship shown in Figures 53 to 56, the supernatant water containing fine coal particles in the top layer of the slurry is discharged by jets of fluid, so that the slurry can be separated efficiently without permitting formation of a covering layer of fine coal particles that would impede removal of water through the bottom drain openings of the hold.

Figures 57 to 61 show another slurry transport ship.

Guide rails 272a and 272b are provided on an opposed pair of side walls of the hatch coaming 271 of a hold 253. A flap 273 is provided between and supported by the guide rails. The flap 273 carries rollers 274 in engagement with the rails 272a, 272b and reinforcing members 275. The flap 273 has such a length that it reaches the upper layer of the coal slurry to be loaded into the hold 253. Means 276 for driving the flap 273 comprises a pair of endless steel cables 277a, 277b reeved around pulleys 278 and turnable along the rails 272a, 272b, and a motor 279 for driving the pulleys 278. The flap 273 is attached to the cables 277a, 277b. With the exception of the above feature, the ship is similar to the one shown in Figure 53.

With this arrangement, the motor 279, when driven, reversibly turns the steel cables 277a, 277b, moving the flap 273 back and forth within the hold 253 along the guide rails 272a, 272b, whereby the fine particle coal slurry in the top portion of the coal slurry in the hold 253 can be discharged into the empty chamber 254 through the drain openings 256. This prevents formation of a covering layer of fine coal particles, permitting water and air to pass through the slurry effectively and allowing water to flow out smoothly from the bottom drain openings 258 of the hold 253.

Thus the transport ship shown in Figures 57 to 61 has the simple construction that a flap for discharging fine particle coal slurry is mounted on guide rails on a hatch coaming, whereby fine particle coal slurry can be separated off and removed smoothly from the upper layer of a coal slurry, and water can be discharged from the bottom of the hold efficiently because of an unimpeded flow of air through the slurry.

Figures 62 to 64 shows another slurry transport ship.

A hold 280 has thereabove a hatch 282 defined by a hatch coaming 281 and closable by an unillustrated hatch cover. A space 284 for accommodating supernatant is provided between lateral partitions 283. The water accommodating space 284 is provided at its lower portion with a drain channel 286 communicating with the interior of the hold 280 through dewatering filters 285. A bilge well 287 in communication with the drain channel 286 is provided in the bottom of double construction of the hold 280. A tray 289 in the form of an angle in cross section extends along the entire inner peripheral surface of the hold 280, i.e. along the front and rear lateral partitions 283 and opposite longitudinal partitions 288. The lateral partition 283 is formed with openings 290 for holding the interior of the tray 289 in communication with the space 284.A bell-mouth 291 for discharging supernatant water is disposed at a lower portion of the space 284. A branch duct 294 of a slurry duct 293 on an upper deck 292 has a forward end (not shown) extending through the lateral partition 283 into the hold 280. indicated at 295 is the lower settling layer (coarse particle coal slurry) of a slurry, and at 296 the supernatant water (fine particle coal slurry) of the slurry.

The coal slurry is charged into the hold 280 through the duct 293 and branch duct 294. Upon the water level reaching the upper end of the tray 289, the supernatant water 296 overflows the tray over the entire interior area of the hold 280, flows through the tray 289 and falls into the space 284 through the openings 290.

When loading in rough weather, pitching or rolling of the ship will raise the level of the supernatant water above the upper end of the tray 289, causing a large amount of the water 296 to abruptly flow into the tray. To prevent this, the tray shown in Figure 64 has an extension higher than the usual height of tray and in the form of a porous filter 297. When the supernatant water remains at a normal level A, the water flows out near the lower end of the filter 297, whereas if the water rises to an abnormal level B due to pitching or rolling, the water flows out over a considerably large area of the filter 297.

With the transport ship of Figures 62 to 64 which is adapted to separate supernatant water containing fine particles (i.e. fine particle coal slurry) from a coal slurry while the slurry is being loaded into the hold, the supernatant water flows into the tray over the entire periphery of the hold and then falls into the water accommodating space through drain openings. The supernatant water therefore flows into the tray gently without entraining coarse particles that will settle for separation. Thus the coal slurry can be separated properly.

Figure 65 shows another transport ship for practicing another method of the invention.

The tranport ship 300 having a number of holds which are defined by longitudinaaa partitions and lateral partitions and each of which is provided thereabove with a separator 21 3 of the same construction as those shown in Figures 44, 46 and 47. The separator 213 has a slurry inlet 220 connected by a flexible tube to a slurry loading duct 301, one end of which is connected to a slurry storage pond 302 on the shore. The loading duct 301 has a binder inlet at a portion thereof close to the pond 302. As is the case with Figures 48 to 52, the duct 301 has incorporated therein granulating means comprising stirring blades for mixing a slurry and a binder together by stirring. The separator 213 has a water outlet 221 connected by a flexible tube to a drain pipe 303, one end of which is connected to an ash removing apparatus 304 on the shore.The ash removing apparatus 304 has a water outlet 305 connected to the pond 302 and an ash outlet 306 connected to a press filter 307.

With the above arrangement, a coal slurry is supplied from the pond 302 through the loading duct 301, while a binder is added to the slurry through the binder inlet of the duct 301. The slurry and the binder are mixed together by stirring and sent toward the separators 213 while coal particles are being granulated. The slurry containing the granules is fed to the apparatus 213 through the inlet 220. As in the embodiment already described, the granules of large size are separated from ash-containing water and placed into the hold. The ash-containing water is discharged through the water outlet 221 and sent through the drain pipe 303 to the ash removing apparatus 304, in which the ash is removed from water by concentration. The water alone is sent to the pond 302 and used again for the preparation of slurry. The concentrated ash is further sent to the press filter 307 and dewatered.

Although fine particles are granulated while loading the coal slurry into the ship in the above embodiment, the coal slurry may be subjected to granulation by an apparatus on the shore near the loading port as seen in Figure 66 and thereafter loaded into a ship.

With reference to Figure 66, a granulating and classifying apparatus 310 granulates coal particles and classifies the granules. The apparatus 310 includes a granulating device 311 for admixing the binder supplied from a binder container 312 with a coal slurry by stirring for granulation. A vibrating screen 313 classifies the granules from the device 311 into three different particle sizes. The coarse granules and somewhat smaller granules separated by the first and second stages of the screen 313 are dewatered by rotary screens 314 and 315 respectively and are further stored in tanks 316 and 317 respectively. The water separated is sent to a water tank (not shown). The granules in the form of fine particles and separated by the third stage of the vibrating screen 313 are subjected to wet classification by a wet cyclone 318. The relatively coarse granules separated are dewatered by a rotary screen 31 9 and stored in a tank 320. The relatively fine granules separated are dewatered by a rotary screen 321 and stored in a tank 322. The water separated off by the rotary screens 319 and 321 is sent to the water tank.

The coal separated from ash-containing water in this way is loaded into a transport ship as it is or as made into a slurry again with addition of water.

Claims (39)

Claims

1. A method of transporting coal comprising classifying coal sent forward in the form of a slurry according to the particle size of the coal and transporting by a ship the coal slurry other than a fraction thereof containing the fine particles not larger than a specified size.

2. A method as defined in claim 1 wherein the coal in the form of a slurry is classified by equipment on the shore at a loading port.

3. A method as defined in claim 2 wherein the coal slurry is classified by an agitation tank provided at its bottom with agitating blades for upwardly directing the contents of the tank.

4. A method as defined in claim 2 wherein the coal slurry is classified with a plurality of classifying basins arranged side by side by introducing the coal slurry into an upstream classifying basin and causing the slurry to flow downstream from basin to basin over the partitions between the basins.

5. A method as defined in claim 2 wherein the fraction containing the fine particles is removed from the coal slurry by passing the coal slurry through a slurry conveying and dewatering tray comprising an upper tray member and a lower tray member disposed below the upper tray member and spaced apart therefrom by a specified distance, at least one of the bottom wall and side walls of the upper tray member being provided with a filter and a multiplicity of drain apertures for discharging water containing the fine particles.

6. A method as defined in claim 1 wherein the coal sent forward in the form of a slurry is loaded into the ship, and supernatant water containing the fine particles is separated from the slurry within its hold.

7. A method as defined in claim 6 wherein the supernatant water containing the fine particles is caused to flow out from openings formed at an upper portion of the hold.

8. A method as defined in claim 7 wherein the supernatant water containing the fine particles is forcibly moved toward the openings.

9. A method as defined in claim 8 wherein the supernatant water is moved by a high-pressure fluid injected into the water.

10. A method as defined in claim 8 wherein the supernatant water is moved by a flap movably mounted on a hatch coaming.

11. A method as defined in any one of claims 1 to 10 wherein the fraction containing the fine particles and separated from the coal slurry is loaded into the ship in the form of a slurry.

12. A method as defined in claim 11 wherein the slurry fraction containing the fine particles is loaded into the ship in a hold thereof separate from the hold loaded with the slurry containing coarse particles.

13. A method as defined in any one of claims 1 to 10 wherein the slurry fraction containing the fine particles and obtained by the classification is solidified by concentration, and the solidified coal is transported by a ship.

14. A method as defined in claim 13 wherein the slurry fraction containing the fine particles is concentrated for solidification by being caused to flow down a slanting surface in circulation.

15. A method as defined in any one of claims 1 to 10 wherein a binder comprising an oil is admixed with the slurry fraction containing the fine particles and obtained by the classification to form granules, and the granules are transported by a ship.

16. A method as defined in claim 15 wherein the granules are transported in the same hold as the coal slurry other than the fine particle fraction.

17. A method as defined in any one of claims 1 to 10 wherein the slurry fraction containing the fine particles and obtained by the classification is sent back to a coal mining area and admixed with the slurry to be transported.

18. A method as defined in claim 1 wherein a binder comprising an oil is admixed with the coal sent forward in the form of a slurry to form granules, and a slurry containing the granules is separated off by classification.

19. A method as defined in claim 18 wherein ash-containing water is separated from the slurry containing the granules.

20. A method as defined in claim 18 or 19 wherein the coal sent forward in the form of a slurry is granulated by equipment on the shore at a loading port.

21. A method as defined in claim 18 or 19 wherein the coal sent forward in the form of a slurry is granulated while being loaded into a ship.

22. A coal slurry transport ship having a hold for loading the coal slurry, the hold being provided with means for dewatering the slurry.

23. A transport ship as defined in claim 22 wherein the slurry dewatering means is a drain tube suspended from the top of the hold and comprising a main body and a draining underwater pump, the main body having a filter in its outer peripheral portion and a water accommodating space in the interior of its bottom, the underwater pump being disposed in the interior of the main body bottom.

24. A transport ship as defined in claim 23 wherein the drain tube is vertically movably suspended from guide tubes mounted on the top of the hold.

25. A transport ship as defined in claim 23 wherein the drain tube is attached to a hatch cover and is turnable between a stored position along the hatch cover and a vertical suspended position.

26. A transport ship as defined in claim 22 wherein the slurry dewatering means comprises a drain opening formed in the bottom of the hold and water guides provided on the side walls and bottom walls of the hold and extending to the drain opening.

27. A transport ship as defined in claim 22 wherein the slurry dewatering means comprises a dish-shaped dewatering frame having a filter at its bottom, a draining pump disposed inside the dewatering frame and a float surrounding the dewatering frame.

28. A transport ship as defined in claim 22 wherein the slurry dewatering means comprises a drain opening formed in the bottom of the hold and a turning arm disposed in an upper portion of the hold and having stirring blades, the turning arm being attached to the lower end of a rotary shaft vertically movably suspended from the top wall of the hold, the rotary shaft having a projection at its lower end.

29. A transport ship as defined in claim 22 wherein the hold is formed in an upper portion of its wall with openings for passing supernatant water containing fine particles of the coal slurry.

30. A transport ship as defined in claim 29 wherein the hold is provided at an upper portion thereof with means for forcibly moving the supernatant water toward the openings.

31. A transport ship as defined in claim 30 wherein the means for forcibly moving the supernatant water comprises nozzles for injecting a high-pressure fluid.

32. A transport ship as defined in claim 30 wherein the means for forcibly moving the supernatant water is a flap movably mounted on the hatch coaming of the hold.

33. A transport ship as defined in claim 29 wherein a tray is provided at an upper portion of the peripheral wall of the hold, and the interior of the tray is in communication through the openings with a space for accommodating the supernatant water.

34. A transport ship as defined in claim 22 wherein the hold is provided with a coal agitating apparatus in its interior.

35. A transport ship as defined in claim 34 wherein the agitating apparatus comprises screw conveyors disposed at the bottom of the hold, and each of the screw conveyors has a plurality of nozzles for discharging a pressurized fluid.

36. A transport ship as defined in claim 35 wherein the pressurized fluid discharging nozzles are arranged helically at suitable spacing.

37. A method of transporting coal substantially as hereinbefore described with reference to the accompanying drawings.

38. A coal slurry transport ship substantially as hereinbefore described with reference to the accompanying drawings.

39. Any novel subject matter or combination including novel subject matter herein disclosed, whether or not within the scope of or relating to the same invention as any of the preceding claims.